Title:	Orbital phase spectroscopy of four high mass X-ray binary pulsars to study the stellar wind of the companion
Authors:	Naik, S. Mukherjee, U. Paul, Biswajit Chol, C.S.
Keywords:	Pulsars: individual (4U 1538-52, GX 301-2, OAO 1657-415 and Vela X-1) Stars: circumstellar matter X-rays: stars
Issue Date:	16-Mar-2009
Publisher:	Elsevier B.V.
Citation:	Advances in Space Research, 2009, Vol. 43(6), p900-904
Abstract:	Our work focuses on a comprehensive orbital phase-dependent spectroscopy of the four High Mass X-ray Binary Pulsars (HMXBPs) 4U 1538-52, GX 301-2, OAO 1657-415 and Vela X-1. We hereby report the measurements of the variation of the absorption column density and iron-line flux along with other spectral parameters over the binary orbit for the above-mentioned HMXBPs in elliptical orbits, as observed with the Rossi X-ray Timing Explorer (RXTE) and the BeppoSAX satellites. A spherically symmetric wind profile was used as a model to compare the observed column density variations. Out of the four pulsars, only in 4U 1538-52, we find the model having a reasonable corroboration with the observations, whereas in the remaining three the stellar wind seems to be clumpy and a smooth symmetric stellar wind model appears to be quite inadequate in explaining the data. Moreover, in GX 301-2, neither the presence of a disk nor a gas stream from the companion was validated. Furthermore, the spectral results obtained in the case of OAO 1657-415 and Vela X-1 were more or less similar to that of GX 301-2.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/3749
ISSN:	0273-1177
Alternative Location:	http://dx.doi.org/10.1016/j.asr.2008.12.011 http://arxiv.org/abs/0812.4519
Copyright:	2008 COSPAR Published by Elsevier Ltd.
Appears in Collections:	Research Papers (A&A)

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